This invention relates to diverter for reversing the direction of flow in a fluid circuit.
Although the new diverter may be used in a variety of fluid circuits, it will be illustrated in reference to a heat exchanger or cooler. A well known type of heat exchanger comprises a cylindrical tank having tube sheets spaced from its opposite ends. The tube sheets are connected by a bundle of tubes which is divided into upper and lower halves by a longitudinal separator such that cooling fluid may enter one end of the tank and flow through one half of the tubes in one direction and the other half of the tubes in the reverse direction so that the inlet and outlet of the tube bundle are at the same end of the tank. Fluid or vapor which is to be cooled, heated or condensed flows over the outside of the tubes in the space between the tube sheets and, of course, there are inlet and outlet connections to this space.
In a practical case, the cooling water which is circulated through the interior of the tubes in the bundle have some dissolved minerals which deposit on the inner walls of the tubes and it is known that this results in scale formation unless the deposit is frequently removed. It is well known that chemical treatment of the cooling water alone is not sufficient to completely prevent sedimentation or fouling. Even when mechanical or chemical cleaning appears to be required infrequently, such as once or twice a year, it is not uncommon to find that the average fouling which occurs between cleaning is sufficient to produce a substantial reduction is heat transferability. In air conditioner systems, for instance, where hot gases are cooled in the heat exchanger and the heat dissipated by means of a water cooling tower, the fouling can result in substantial extra energy being required in the system.
One method of coping with tube fouling is to force brushes through the tubes one or more times per day in opposite directions. A method and means for propelling brushes through the tubes without accessing the interior of the heat exchanger is described in U.S. Pat. No. 3,319,710. In the patent each of the tubes in the bundle terminates in a cage. Cages at corresponding ends of the tubes have brushes parked in them at a given time. When it is desired to clean the tubes, flow direction through them is reversed and the brushes are propelled through the tubes to the cages at the opposite ends of the tubes, thus cleaning out the sedimentation.
The change in flow direction necessary to propel the brushes is accomplished at the present time by switching a four-way valve outside of the heat exchanger so that the inlet thereof becomes the outlet temporarily and the outlet becomes the inlet. Presently available four-way valves are constructed so that a large number of external connections are necessary to achieve flow reversal by actuating the valve. At least eight and sometimes as many as twelve elbows are required for typical installation of a four-way valve in a flow reversal circuit. As those practicing the art know, this has resulted in a maze of piping in the vicinity of the valve which occupied an inordinate amount of space and had an exceedingly unattractive appearance.